#define _CRT_SECURE_NO_WARNINGS
class UnusualAdd {
public:
    int addAB(int A, int B) {
        if (A == 0)
            return B;
        else if (B == 0)
            return A;
        else
        {
            return addAB(A ^ B, (A & B) << 1);
        }
    }
};